<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      var num = 10;
      console.log((num += 10)); // 20

      console.log((num -= 10)); // 10

      console.log((num *= 10)); //100

      console.log((num /= 10)); //10
    </script>
  </body>
</html>
